Tyrosinase activity (Monophenol, dihydroxyphenylalanine: oxygen oxidoreductase EC 1.14.18.1) in vitiligo and normal epidermal homogenates of skin from human beings was measured by estimating beta 3,4-dihydroxyphenylalanine (dopa) by a highly sensitive fluorometric method described in this paper. The tyrosine activity in the vitiligo skin was about 4 to 37% of corresponding normal skin. The activity of tyrosinase in normal human skin from different individuals and from different regions of the body was in the range of 4 to 140 picomoles of beta 3,4-dihydroxyphenylalanine formed per min/mg protein of epidermal homogenate. The enzyme from vitiligo and normal skin was severely inhibited by substance(s) of low molecular weight. The enzyme exhibits a lag of about 4 hr in the absence of added beta 3,4-dihydroxyphenylalanine and 1 hr in presence of 5 microM dopa. Tyrosinase from the normal and vitiligo skin was inhibited by excess concentration of tyrosine. The homogenates from vitiligo skin could synthesize melanin from C14(U)-L-Tyrosine. The rate of tyrosine incorporation into melanin by the epidermal homogenates is increased by 3,4-dihydroxyphenylalanine (dopa) disproportionate to its effect on tyrosinase activity. Based on the data presented in this paper it is concluded that melanocytes are present in the vitiligo skin. A tentative hypothesis is put forward to explain the lack of melanin synthesis by the vitiligo skin under in vivo conditions, although melanocytes are present.
Thirty‐nine patients with previously untreated squamous cell carcinoma of the buccal mucosa were treated by two polychemotherapeutic regimens. The first regimen consisted of bleomycin and methotrexate (BLM‐MTX): bleomycin 30 mg was given intravenously twice weekly, and methotrexate 25 mg intravenously twice weekly for 2 1/2 and two weeks, respectively. The second program consisted of Cytoxan (cyclophosphamide), methotrexate and 5‐FU (CMF): methotrexate 25 mg twice weekly for two weeks, Cytoxan 100 mg/day for two weeks, and 5‐FU 500 mg twice weekly for 1 1/2 weeks. All of the patients were evaluated one week after completion of their chemotherapy regimen. Although the patients were not randomly allocated to either treatment, they matched in age and extent of disease. High response rates (88.9%) were noted with the BLM‐MTX combination, which is comparable to the best responses reported previously using cis‐platinum, Oncovin (vincristine), and methotrexate. This may suggest that buccal cancers are highly sensitive to an initial treatment by BLM‐MTX, and therefore the authors highly recommend its use as preoperative adjuvant therapy in patients who present with Stage III and IV (Mo) disease.
This paper reviews a short series of patients with distal hypospadias who were treated by Mustardc's one‐stage technique, to which we have added a minor modification by tubing the flap before penis tunnelization. A single‐stage repair has obvious advantages over a more conventional multistage procedure. The advantage of tubing the flap is early healing, and it reduces the risk of fistula formation, even in the presence of infection, which is very common in this country. The new urethral opening is situated at the fossa navicularis, and the functional results are excellent.
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